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GT40 heads and HO intakes and headers

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    GT40 heads and HO intakes and headers

    Hey guys, I just picked up HO upper and lower intakes and factory 87-93 shorty headers. I'm trying to go back to stock and take off all this GT40 stuff but I don't want to pull my GT40 3 bar heads if I don't have to... do any of y'all run GT40 heads and the stock stuff, or ever heard of someone doing so?

    I'm going for reliability and gas mileage, so the GT40 stuff just isn't working out with the stock ECM and AOD. Constant header problems, every 10,000 miles they start leaking again. It's slow off the line, overheats in the summer with the A/C on, and is a gas hog. I liked it better when it was HO factory matched components. Anyone else feel this way after installing the GT40 stuff or am I nuts?

    I have already replaced the engine harness, MAP, IACV, TPS, COIL, Distributor, ICM, plugs/wires/cap/rotor, EGR valve, EVR solenoid, tried 3 different ECMS, ran seafoam and gas treatments, checked the timing, checked for vacuum leaks, checked fuel pressure, checked grounds, new battery, etc etc.

    I just think this car needs a standalone ECM and a tune and a 3000 stall to feel right. I definitely wanted to do those when I was younger, but now I just want my old girl reliable and torquey!
    1989 Lincoln Town Car - "Anabelle" - Original block, .030 over with SpeedPro pistons, rods fitted with ARP hardware, FRPP +volume oil pump, GT-40 3bar heads, Crane 1.72 rockers, 89' Fox cam, 93' Cobra lower intake, Explorer upper and 65mm TB, 93' Lightning EGR spacer, K&N intake kit from a 4.0L Ranger, 19lb/hr injectors w/ 87 Mark VII ECM, cat/smog deletes, Big Brake conversion, 3.55 K-Code Trac-Lok/Disc brake rear axle, CVPI LCA's w/1" sway bar in rear, wagon front sway bar, BBK 2.5" off-road H-Pipe, Flowmaster super 40s, HPP wheels, 3G alternator w/LMR.com wiring kit, gear reduction starter conversion, Best 1/4 time: 16.0 @ 85mph.

    #2
    Seems weird, although the speed-density may be what's screwing you. I did similar stuff to my previous '90 vic and it ran pretty good. I did lose some low-end but the damn fool thing pulled like a train above 2500 or so. Better gears and a stall would've made it a beast. Can't say how great it was on gas because i literally only made it through like a tank and a half before some yahoo wrecked me, although it didn't seem to be notably worse than when it was stock. Anyhow, i'd say your best bet is to do a MAF conversion, tune with something like a tweecer or quarterhorse, or just dump the stock junk back on. You could probably get away with leaving the heads on, gt40's aren't terribly exotic and shouldn't effect you that much.

    Comment


      #3
      Originally posted by knucklehead0202 View Post
      Seems weird, although the speed-density may be what's screwing you. I did similar stuff to my previous '90 vic and it ran pretty good. I did lose some low-end but the damn fool thing pulled like a train above 2500 or so. Better gears and a stall would've made it a beast. Can't say how great it was on gas because i literally only made it through like a tank and a half before some yahoo wrecked me, although it didn't seem to be notably worse than when it was stock. Anyhow, i'd say your best bet is to do a MAF conversion, tune with something like a tweecer or quarterhorse, or just dump the stock junk back on. You could probably get away with leaving the heads on, gt40's aren't terribly exotic and shouldn't effect you that much.
      Oh yeah, both my '90s have been california cars with the weird unicorn MAF computer that only happened here in '90-'91 so they take a bit more kindly to modification. Cool thing is that a MAF a9 computer is plug and play.

      Comment


        #4
        You might try restricting the intake tube to a 65mm or smaller somewhere along the line between the airbox and the intake. Putting the old intake manifold back on would probably sort the issues. I've also thought that putting 19# injectors on with the GT40 stuff would be enough to kinda balance the difference in air with fuel on a stock lopo cam.

        Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
        rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
        Originally posted by gadget73
        ... and it should all work like magic and unicorns and stuff.
        Originally posted by dmccaig
        Overhead, some poor bastards are flying in airplanes.

        Comment


          #5
          yeah its the speed-density running too lean. I had similar problems with mine. Mass air fixed it nicely, the tune made it better. Lean fuel mix makes it run hotter too, and burn more fuel even though that doesn't seem to make sense.

          Try a 60mm throttle body before you get too far into it. That stock lower is quite simply awful.
          86 Lincoln Town Car (Galactica).
          5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

          91 Lincoln Mark VII LSC grandpa spec white and cranberry

          1984 Lincoln Continental TurboDiesel - rolls coal

          Originally posted by phayzer5
          I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

          Comment


            #6
            Originally posted by gadget73 View Post
            yeah its the speed-density running too lean. I had similar problems with mine. Mass air fixed it nicely, the tune made it better. Lean fuel mix makes it run hotter too, and burn more fuel even though that doesn't seem to make sense.

            Try a 60mm throttle body before you get too far into it. That stock lower is quite simply awful.
            I do have a 60mm laying around, I'll try that first. Also forgot to mention in Open Loop mode, when the engine is still cold, she runs like a scalded dog!! Very noticeable when the ECM goes into closed loop, the engine falls on it's butt. I didn't know you tuned yours, did you use a tweecer?

            I also have a set of 24lb injectors, but I suspect that would make things worse?
            Last edited by 89LincolnTWNcar; 06-07-2018, 09:05 AM.
            1989 Lincoln Town Car - "Anabelle" - Original block, .030 over with SpeedPro pistons, rods fitted with ARP hardware, FRPP +volume oil pump, GT-40 3bar heads, Crane 1.72 rockers, 89' Fox cam, 93' Cobra lower intake, Explorer upper and 65mm TB, 93' Lightning EGR spacer, K&N intake kit from a 4.0L Ranger, 19lb/hr injectors w/ 87 Mark VII ECM, cat/smog deletes, Big Brake conversion, 3.55 K-Code Trac-Lok/Disc brake rear axle, CVPI LCA's w/1" sway bar in rear, wagon front sway bar, BBK 2.5" off-road H-Pipe, Flowmaster super 40s, HPP wheels, 3G alternator w/LMR.com wiring kit, gear reduction starter conversion, Best 1/4 time: 16.0 @ 85mph.

            Comment


              #7
              To get the surge out of my p-head, systemax1 lower, HO upper/tb/cam/19lb/LSC ECM combo, I bumped the fuel pressure 4-5psi with an adjustable regulator. It gave me the increase fuel demands i needed on the same stock WOT maps. I'm sure my A/F wasn't even close to perfect, but it's cheaper than the alternative, and ran pretty darn good.

              Comment


                #8
                QuarterHorse on mine. You can run the 24# as long as you program the ECM for it. I believe those do work on the Mark VII ECM too.
                86 Lincoln Town Car (Galactica).
                5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                91 Lincoln Mark VII LSC grandpa spec white and cranberry

                1984 Lincoln Continental TurboDiesel - rolls coal

                Originally posted by phayzer5
                I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                Comment

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